A/T - 4L80E Electrical Diagnosis
TECHNICAL BULLETIN # 117TRANSMISSION: 4L80-E
SUBJECT: Electrical Diagnosis Information
APPLICATION: GM
The 4180-E is a fully electronically controlled transmission. All upshifts, downshifts, converter clutch applications and line pressure are controlled by activating solenoids. The following pages show the procedures and specifications for internal transmission electrical component testing including solenoids, temperature sensor & pressure switch manifold.
TEMPERATURE SENSOR TESTING
Using a digital ohmmeter check the resistance between terminal G and H (See Figure 1) and compare the reading to the chart.
Note
Transmission Sensor - Temp To Resistance (approximate)
4L80E INTERNAL WIRING DIAGRAM - Figure 1
Quick Checking The 4L80-E
1. Disconnect the case connector.
2. Place gear selector in the OD position.
3. Supply a fused (10 amp) 12 volt supply to terminal C of the case connector.
4. Ground terminal A for 1st gear.
5. Remove the ground from terminal A to shift to 2nd gear.
6. Ground terminal E to shift to 3rd.
7. Ground terminal A and E to shift to 4th.
FAILURE OF THE TRANSMISSION TO RESPOND TO "QUICK CHECK" INDICATES A POSSIBLE OR INTERNAL MALFUNCTION. REFER TO FIGURE 3 FOR SOLENOID MECHANICAL FAILURES.
Resistance Values
4L80-E SOLENOID A & B MECHANICAL FAILURE DIAGNOSIS
(ASSUMES OD RANGE IS SELECTED AND NO DEFAULTS PRESENT)
PRESSURE SWITCH MANIFOLD CHECK (PSM)
The PSM contains 5 normally open pressure switches which are used to indicate the manual control valve position to the PCM. Use the chart to check the PSM.
IMPORTANT
Since these switches are activated by hydraulic pressure, the engine must be running and the transmission must be capable of producing line pressure.
FORCE MOTOR/PRESSURE COMPARISON